Simultaneously Promoting Proton Conductivity and Mechanical Stability of SPEEK Membrane by Incorporating Porous g–C<sub>3</sub>N<sub>4</sub>

Proton exchange membranes are widely used in environmentally friendly applications such as fuel cells and electrochemical hydrogen compression. In these applications, an ideal proton exchange membrane should have both excellent proton conductivity and mechanical strength. Polymer proton exchange mem...

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Bibliographic Details
Main Authors: Xiaoyao Wang, Benbing Shi
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Membranes
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Online Access:https://www.mdpi.com/2077-0375/15/7/194
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Summary:Proton exchange membranes are widely used in environmentally friendly applications such as fuel cells and electrochemical hydrogen compression. In these applications, an ideal proton exchange membrane should have both excellent proton conductivity and mechanical strength. Polymer proton exchange membranes, such as sulfonated poly(ether ether ketone) (SPEEK) membranes with high ion exchange capacity, can lead to higher proton conductivity. However, the ionic groups may reduce the interaction between polymer segments, lower the membrane’s mechanical strength, and even cause it to dissolve in water as the temperature exceeds 55 °C. The porous graphitic C<sub>3</sub>N<sub>4</sub> (Pg–C<sub>3</sub>N<sub>4</sub>) nanosheet is an important two–dimensional polymeric carbon–based material and has a high content of –NH<sub>2</sub> and –NH– groups, which can interact with the sulfonic acid groups in the sulfonated SPEEK polymer, form a more continuous proton transfer channel, and inhibit the movement of the polymer segment, leading to higher proton conductivity and mechanical strength. In this study, we found that a SPEEK membrane containing 3% Pg–C<sub>3</sub>N<sub>4</sub> nanosheets achieves the optimized proton conductivity of 138 mS/cm (80 °C and 100% RH) and a mechanical strength of 74.1 MPa, improving both proton conductivity and mechanical strength by over 50% compared to the SPEEK membrane.
ISSN:2077-0375